Difunctional tetrafluorobenzene

ABSTRACT

2,4,5,6-tetrafluorobenzene compounds having Beta -hydroxyethyl, Beta -acetoxyethyl or vinyl difunctionality are disclosed. The Beta -hydroxyethyl and Beta -acetoxyethyl functional compounds are precursors to a divinyl-tetrafluorobenzene which can be reacted with *SiH compounds to provide siloxanes having *SiCH2CH2C6F4CH2CH2Si* linkages.

United States Patent Pierce et al.

DIFUNCTIONAL TETRAFLUOROBENZENE Inventors: Ogden R. Pierce; John R.Greenwald, both of Midland, Mich.

Appl. No.: 67,619

US. Cl. ....260/650 F, 260/46.5 P, 260/4482 D, 260/488 CD, 260/618 D,260/825 Int. Cl ..C07c 25/04 Field of Search ..260/488 CD, 650 F Jan.30, 1973 [56] References Cited UNITED STATES PATENTS 3,046,313 7/l962Pummer et al. ..260/650 F Primary Examiner.Howard T. MarsAttorney-Robert F. Fleming, Jr., Laurence R. Hobey, Harry D. Dingman,Howard W. Hermann and Norman E. Lewis [57] ABSTRACT2,4,5,6-tetrafluorobenzene compounds having B- hydroxyethyl,B-acetoxyethyl or vinyl difunctionality are disclosed. TheB-hydroxyethyl and B-acetoxyethyl functional compounds are precursors toa divinyltetrafluorobenzene which can be reacted with SiH compounds toprovide siloxanes having SiCH CH C F,CH CH Si linkages.

1 Claim, No Drawings DIFUNCTIONAL TETRAFLUOROBENZENE The inventionherein described was made in the course of, or under, a contract orsubcontract thereunder with the United States Air Force.

This invention relates to novel dlfunctional tetrafluorobenzenecompounds.

More particularly, the invention is directed to tetrafluorobenzenecompounds of the formula in which each R is the same and is selectedfrom the group consisting of the fl-hydroxyethyl radical, the B-acetoxyethyl and the vinyl radical.

The l,3-bis( B-hydroxyethyl)-2,4,5 ,6- tetrafluorobenzene species isprepared by reacting 1,3- dichloro-tetrafluorobenzene with butyl lithiumto obtain a reaction product which is then reacted with ethylene oxide.Acetylchloride is reacted with the [3- hydroxyethyl compound to preparedl,3-bis(B-acetoxyethyl)-tetrafluorobenzene which in turn is pyrolyzed toyield 1 ,3-divinyl-tetrafluorobenzene.

Divinyltetrafluorobenzene is reacted with functional SiH compounds inthe presence of a platinum catalyst to yield silcarbanes of the formulaE SiCH,CH C F4CH CH Si Hydrolysis and condensation of silicon-bondedchlorine in the silcarbane produces siloxane elastomers, such as [311(His l SiCHgCHzCaFHCHzCHz LJJH. H

which are useful as solvent-resistant sealants.

The following examples are illustrative of the invention delineated inthe claims.

tents of the flask to -76 C., 440 grams of 15.2 percent butyllithium inhexane was added very slowly. Addition was complete in 3 hours. Thereaction mixture was stirred at dry ice temperature for an additional 3hours, after which grams of ethylene oxide was added. This reactionmixture was stirred at dry ice temperature overnight and allowed to warmgradually to +20 C. One-half liter of dilute hydrochloric acid was addedand the phases were separated. The organic layer was washed with water,dried and filtered to remove solids. After evaporation of the solventand recrystallization from carbon tetrachloride-toluene mixture, a whitecrystalline solid having a melting point of l03.5-104.5 C. was obtainedThe structure,

HOCHzCHr -CH2CH2OH F was confirmed by mass spectral and infraredanalysis.

EXAMPLE 2 Preparation of yethyl)tetrafluorobenzene.

Acetyl chloride (40 grams) was slowly added to an' ice water cooledmixture of 28 grams of l,3-bis(/3- hydroxyethyl)-tetrafluorobenzene and40 grams of pyridine in 250 ml. of ether. After addition of the acetylchloride, the ice water bath was removed and the mixture was allowed tostir for an additional hour. Water (150 ml.) was added and the phaseswere separated. The ether phase was washed with water and dried overanhydrous CaSO After filtration the ether was evaporated and the residuewas fractionated to yield 29.4 grams of 1,3-bis(B-acetoxyethyl)tetrafluorobenzene having a boiling point ofC./0.7 mm Hg.

EXAMPLE 3 Preparation of l,3-divinyl tetrafluorobenzene.

A vertical quartz tube (1 inches-dia. and l8 inches long) was packedwith l30 grams of 3/16 inches dia. alumina spheres and heated to 550 C.Nitrogen flow was adjusted to l00-l50 ml./min. The diacetate product ofExample 2 was added dropwise to the top of the tube. This pyrolysisyielded a yellow liquid which was dissolved in ether, washed severaltimes with water and dried. The solvent was evaporated and the residuefractionated to obtain 1,3-divinyl tetrafluorobenzene having a boilingpoint of 62 C./5 mm Hg.

EXAMPLE 4 The l,3-divinyl tetrafluorobenzene product of Example 3 wasreacted with 3,3,3-trifluoropropylmethylchlorosilane in the presence ofchloroplatinic acid to obtain an an organosilicon compound of thel,3-bis(B-acetoxformula cm" -61 oisiomomctmomcmshci (1H2 CH2 CH1 CH1(31% I CFa This compound was cohydrolyzed with 3,3,3- trifluoropropylvinyldichlorosilane by addition in an ether solution to water. Thecohydrolzate was condensed by the addition oftetramethylquanidine-acetic acid catalyst to yield a hydroxy-terminatedcopolymer of the formula (EH1 CH: CH1 C 2 C 2 C Fa C C a When compoundedwith silica filler and cured by means of benzoyl peroxide and heat thepolymer was a strong elastomeric material.

1. A compound of ihe formula

